"We have continued our studies on delineating the role of human herpesvirus 8 (HHV8) in the pathogenesis of Kaposi's sarcoma (KS). Over the past year, we have pursued several projects in this area. Firstly, we completed and published a study which looked for evidence of HHV8 infection in patients with a group of autoimmune blistering skin diseases (pemphigus type). This work was based on preliminary studies by others suggesting that HHV8 played a role in the development of these diseases. However, we found no evidence of HHV8 infection in persons with all known forms of pemphigus. Secondly, we have spent considerable effort recently in trying to establish good in vitro model systems to study biologic effects of HHV8 on cells derived from skin. This work has included attempts at infecting human endothelial cells, human PBMC, and human foreskin that had been engrafted on SCID mice. Good infection has not yet been achieved by our group (as well as by most others working in this field) and, as of now, we have attributed these failures to either poor stocks of infectious virus and/or undefined idiosyncracies required for robust HHV8 infection that are not being supplied in tissue culture situations. As a spin-off from this work, however, we have developed a novel system to reliably and quantitatively detect single cells lytically infected with HHV8. This is done using monoclonal antibody staining and FACS analysis. This latter work has recently been submitted for publication. Current studies are focused on determining the phenotype and function of HHV8-infected blood cells in patients with KS (using our new detection system), defining cell-mediated immune responses directed against HHV8, and creating better models to study HHV8-induced pathogenesis, e.g., transgenic mouse models. These studies should contribute to understanding on how HHV8 may cause KS and aid in the design of novel antiviral and immunotherapeutic treatments for patients with this disease. ""HIV/AIDS"""